Peristaltic pumps which permit precise dosage of the liquid to be administered, for instance to a patient in the form of a perfusion, are known as much in research applications as in therapeutic employment. One will find in patent documents U.S. Application No. 4 715 786 and WO 88/10 372 descriptions of peristaltic pumps, the principle of which is well known and which generally consists in employing an elastically deformable tube to be locally crushed against a sump by means of a rotor equipped with revolving rollers and thus sucking in, then expelling the liquid contained in the tube coming from a reservoir. By varying the speed of rotation of the rotor, one may modify the pump discharge. Such discharge may even be programmed over a time period, this as a function of the requirements established by the illness to be cared for or by the experiment which is to be carried out.
Peristaltic pumps equipped with a single tube or flexible pipe exhibit the shortcoming of discharging the liquid which they are intended to transport in a sinusoidal manner, thus irregularly. In order to overcome this problem, there has been proposed the simultaneous employment of two coupled pumps provided with two flexible pipes placed in parallel on which act respectively two rotors provided with rollers. A first pump of this nature is described in the patent document WO 82/04 291 where the rollers on one rotor are angularly offset relative to the rollers of the neighbouring rotor. A second such pump is described in the patent document GB 1 595 901 where the two rotors exhibit coaxial rollers two by two and where the flexible pipes are offset relative to one another in a manner such that when a roller of the first rotor crushes the first pipe in the middle of its active length, the second pipe is simultaneously crushed by two rollers of the second rotor at the beginning and at the end of its active length. Whatever be the solution chosen, it will be understood that, as described, one obtains a much more regular discharge since the sinusoidal discharges given by the two pumps taken independently are offset in time and compensate one another so as to obtain a substantially constant discharge.
The document Life Support Systems (1983), 1, 23-28 describes a peristaltic pump which is implantable into the body. From this particularity there ensues the fact that all components of the pump are hermetically encapsulated in a case of titanium. The pump reservoir is filled in a percutaneous manner by means of a syringe. The driving motor of the pump is of the stepping type. It is energized by a time base followed by a frequency divider and a battery. The pump is externally programmable by means of a control apparatus coupled by magnetic induction to the pump.
The patent document FR-A-2 479 692 (=U.S. Application No. 4 692 147) also describes a peristaltic pump which is implantable into the body, the generic characteristics of which respond in all points to those described in the preceding paragraph.
The peristaltic pumps known from the documents cited hereinabove exhibit construction principles which generally are closely related to the definition given in the first paragraph of this description and which partially describes the pump according to this invention. At the same time, none of the cited pumps and generally no other pump currently known in practice is susceptible to be portable, for instance on the human body for the slow and continuous injection of medicinal preparations. The prior art pumps are heavy and voluminous and if they are employed for purposes of perfusion, are arranged on a table in proximity to a patient prone on a bed.
In contrast to this, the pump according to this invention is portable next to the body, this enabling a patient to move around and even to attend to his usual occupations. To attain this purpose, the pump of the invention is a miniature pump taking up little space. Another aim of the pump according to the invention is that of being inexpensive to such a point that it may be thrown away following use, thus avoiding all risk of contamination. Yet another purpose of the pump according to the invention is that of having two modules, a pump module and a motor module which are separable by the practitioner himself who could be either a medical doctor or a nurse, this in order to enable sterilization of the pump module and/or choice of a motor module adapted to the illness to be cared for.